Preparation of rags for paper making



Aug. 13, 1940.

H. F. LEwls Er AL 2,211,138

PREPARATION 0F RAGS FOR PAPER MAKING Filed Doc. 4, 1935 2 Sheets-Sheet 1 H. F. LEWIS El' AL PREPARATION 0F RAGS FOR PAPER MAKING Aug. 13, 1940.

Filed uw. 4, 1935 2 sheets-sheet 2 Patented Aug. 13, 1940 UNITED STATES PATENT OFFICE PREPARATION F BAGS FOB PAPER MAKING Wisconsin Application December 4, 1935, Serial No. 52,748

s claims.

Our invention relates to improvements in the preparation of rags for paper making and its principal objects are to provide a process and apparatus by which the rags are freed from dyestuffs or other undesirable materials which would interfere with the iull utilization of the rag stock in the manufacture of paper, to reduce the time required in the preparation of the paper stock from rags, to provide an improved quality of stock from rags, and, in general, to provide an improved process and apparatus of the character referred to.

Heretofore, so far as we are aware, the preparation of rags for use in the making of papermaking stock has involved a series ot operations `carried on in a more or less disconnected v/ay and at diilerent times with different equipment located in dinerent parts of the paper mill. Buch prior art processes have involved the handling of 1 the rags repeatedly and the transporting oi' the material in more or less solid form from place to place in the mill imtil the various series of disconnected steps of the rag preparation process have been completed. Also..so far as we are aware, no thoroughly successful process has been worked out for the purpose of eliminating certain types 't coloring matter by which the cloth had been originally dyed. Also, in addition to elimination of the dyestuils. we believe that no very practical method has ever been evolved for the purpose of eliminating waxes, other loading materials and the like.

One important feature of our invention oonsistsinthecsrrylngonoitheentireseriesof rag preparation steps as a practical continuous process, the term "continuous" in this sense. meaning treating or working a batch of stock in a single apparatus, or apparatus group without any material interval between the consecutive steps of the process.

According to the preferred method of operation. the rags are first treated in a beating engine or other suitable apparatus for divellicating the ilbers, i. e., disintegrating the rags to such an extent bymechanical action that the individual ilbers are separated from each other and are exposed to any chemical treatment to which it may be desirable to subject the stock in order to remove the undesired dye or other materials.

After the ilbers have been suiliciently separated. they may be ilrst washed and then they can be treated with the necessary chemicals for loosening and removing the adherent dyestun or other foreign matter adhering to the individual bers. After the chemical treatment has (CI. d218) been completed the fibers are then thoroughly.

washed and subjected to any other treatment which they may require before they are introduced into the paper-making batch. During all of these steps of the process the fibers being water borne may be vigorously agitated so that each individual ilber is acted upon and is fully responsive to the particular treatment to which it is being at that time subjected. In view of the fact that certain materials, particularly certain dyestuils, require chemical treatment at high temperatures. frequently higher than. that of boiling water. the equipment used in theV process must be enclosed and capable of withstanding substantial pressures above that oi' the atmosphere.

As a specic example of an equipment which may be used for practicing the process, we have disclosed herein a modified beater of the type disclosed in the U. B. Patent to Seaborne, No. 1.691.308, issued November 13, 1928, which type lends itself particularly well to a construction which will withstand the pressures to which the stock may have to be subjected during the Process. t1In the drawings accompanying this applica- Fig. 1 is al vertical section through the center of the beater.

Fig. 2 is.an underside plan view of the same. looking in the direction of the arrows 2 2 in .Bisasectionalplantaken ontheline of Fig. l,

4 is a fragmentary section taken on the e 4 4, and

Fig. 5 is a section taken on the line 5-8 of Fig. 2.

Describing nrst the apparatus used in carrying out the process. it willbe seen that the equipment is supported upon a series oi' three legs I0. to the upper ends of which is bolted a heavy plate or disc l I. which constitutes the bottom wall or floor of the beater. Said plate Ill at its outer edge is made with an upwardly extending nange which forms a fillet or radius I2 around the outer edge of the disc Il and'between the disc and the vertical wall il which forms the inside wall of the beater.

The upper end of the cylindrical sidev wall I 3 is made with a radius i4 and supports a closure ring il, the outer edge of which is united to an outer cylindrical casing I8 spaced from the inside wall I3 to form a Jacket for the introduction of heating, and, if desired, cooling duid. The lower Fig Fis 8-3 Fig lin end of the hollow jacket is closed by a ring |1 to which the lower ends of the cylindrical walls i3 and |8 arek suitably united.

The upper end of the beater is enclosed by a top plate or disc |8 which is equipped with a suitable illling opening normally closed by means oi' a bolted cover 8. Said top plate |8 is also equipped with a pocket in its underside, formed by a circular depending iiange or projection 28, on the underside of lwhich there is suitably secured a screen 2|, preferably of mesh equivalent to that of a Fourdrinler wire. The upper wall of the pocket is apertured to receive the lower end of a wash-water discharge pipe 22.

Within the beater chamber and concentric therewith, there is adjustably supported a stator whichl comprises an open topped bowl or curved annulus 23 on the underside of which there is arranged in a horizontal plane an annular series of stationary inclined spaced knives 24, see also Fig. 4. These knives 24 cooperate with a similar set of oppositely inclined knives 25 carried by a rotor 28. The rotor 28 is supported and rotated in a fixed vertical position, the adjustment between the knives being effected by elevating or depressing the stator bowl 23. This is effected by carrying the stator on a series of three lugs 21 which in turn are supported by vertically adjustable posts or columns 28. Theshouldere`d heads or upper lends'of these columns 28 are flxedly secured in the lugs 21 by means of lock screws 28, the lower parts of said columns being cylindrical and extending downwardly through stuihng boxes 38 in the lower base plate li. The depending ends of the posts 28 are threaded as shown at 3| and extend through cooperating threaded collars 32. Each of said collars is supported so as to nt snugly between the spaced upper and lower arms 33 and 33 of a bracket 35 bolted to the underside of the base plate I|. Integral with each of the collars 32 is a toothed flange 3 8 which cooperates with a chain 31 trained around all three of the sprockets 38.

The chain 31 is alsoV trained around a sprocket 38 keyed to the end of a vertical shaft 38, journaled in brackets 48 and 4|, bolted to the exterior wall I8 of the beater jacket. To the upper end of the shaft 39 there is keyed a hand wheel 42, by means of which the shaft 38 can be rotated, which rotation by means of the chain 31 and the sprockets, causes a uniform rotation of the threaded sprockets 38 on the threaded lower ends of theA supporting posts 28, so that the bowl can be adjusted up and down in the beater. Any slack which exists or develops in the chain 31 may be taken up by means of an idler pulley 43 which is mounted in a horizontally adjustable bracket 44, bolted to the underside of the-base plate .As has been previously stated, the moving knives 25 of the beater are mounted on the lower end 28 of the rotor. This lower end comprises a horizontally extending flange portion 45 which carries the knives, and a more or'less conical portion, the upper end of which is in the form of a hub 48. The hub 48 is keyed to a central vertical shalt 41, the lower end of which extends through a stuiilng box-48 in the base plate il. and the upper end extends through a stuiiing box 48 in the cover plate I8. Above the hub 48 there is also keyed to the shaft 41 a tapered or hub-like. part 88 on 'the exterior of which there is formed' a screw thread 8| which serves the purpose of a propeller for moving the central portion ofthe stock in amore or less vertical direction.

'.I'he shaft 41 is driven at its lower end by means of the following train of mechanism. Beneath the base plate of the beater, there is a frame plate 52 which is bolted to the lower ends of the brackets previously described. On the underside of said plate there is mounted a cover 53 which carries at its lower side an enclosed bearing 54 for the lower end of shaft 1 and also serves to enclose the gearing for driving the shaft. Said gearing comprises a large beveled gear 55 keyed to the lower end of the shaft 41 and a beveled pinion 58 keyed to the end of a shaft 51, Journaled in a bearing 58 at one side of the plate 52,and in a bearing 59 carried by a bracket 88, secured to the inside of the base of one of the main supporting legs I0. The shaft 55 is rotated by means of a pulley 8| driven by a belt not shown.

Ih order to prevent clogging of the screen 2|, we prefer to equip the underside of said screen with a two-bladed scraper 82 which is keyed to the end of a vertical shaft 83, extending through a stuiilng box 84. The upper end of the shaft 83 is supported in a bearing 85, at the upper en`d of a bracket 88, formed as a part of the upper side of the cover member 81. On the extreme upper end of the shaft 83 there is keyed a grooved pulley 88 driven by a round belt 88 passing around a corresponding groove 10 in the upper end of the main shaft 41.

Steam for heating purposes or cold water for cooling purposes may be admitted to the jacket thi Jugh a pipe 1| and the water of condensation or other water' admitted to the jacket can be removed through a discharge pipe 12. In the case of steam, the water of condensation passes out through a suitable trap 13.

In order to prevent the rags or rag particles from collecting at the .inside edges of the knives 25, we prefer to secure to the lower edge of the bowl 23 of the beater. a pair of cutting knives 14.

Also, in order to obtain a proper distribution of stock, it may be -advisable to employ one or more cam-like projections 15 on the rotor 28.

In certain cases, we dnd it advisable also to secure to the outer edge of the lower flange part 45 of the rotor one or more, in this case, three, plow-like members 18, wedge-shaped in vertical cross-section, which serve to plow up from the bottom of the beater any accumulation of rags or stock so that the same will be properly circulatedin the tank of the beater.

In the bottom plate at one side of the same, there is provided an opening 11, large enough to oil'er no material obstruction to the flow of ilnished stock. 'I'he lower end of said opening is normally closed by means of a mushroom valve 18 seated in a ring 18, secured to the upper end of a housing 88 which is bolted to a ilange on the underside of the base plate and surrounding the opening 11. Said housing 88 is in the form of a hollow elbow so that the lower end of the stem 8| which carries a puppet valve 18 may extenfi downwardly vertically and outwardly intoa control cylinder 82. Within the control cylinder 82 there is adapted to reciprocate a piston 83 fixed to the end of the valve stem 8|, so that by suitable valve arrangements duid under pressure admitted to or discharged from the pipes 84 and 85 can be employed to either open or close the valve 18.

On the lower end of the elbow housing 88 there is secured a hollowntting 88 to which steam may be admitted through a valve 81, or water may be admitted through a valve 88. On the outer end of the fitting 88 there is mounted a large gate valve 89. The valve 89 is closed whenever it is necessary to admit steam or water into the beater. When it is desired to discharge the nnished stock, the valve 89 is opened.

The above described apparatus is capable of use in various ways to suit the particular stock which is to be treated and to suit the particular treatment to which the stock is to be subjected..

We will now illustrate the application of the process and apparatus in the treatment of cotton rags dyed with indigo or a combination of indigo with some other dye.

The rags are first cut to size with the usual mill rag cutter after which a charge of the cut rags, weighing 25 pounds is introduced into the beater with about 300 pounds of water. By this time the bowl of the beater is elevated to its fullest extent so that the beater knives 24 and 25 are separated to the maximum extent. The beater is started in operation and after about twenty or twenty-five minutes the fibers are found to be sufilciently dlvelllcated.

If the rags have been dusted the chemical treatment is immediately begun, but if the rags have not been dusted, clear water is admitted through the valve 88 and flows out of the beater through the screen 2| and waste'pipe 22, carrying with it any soluble dirt or other substance which can pass out through the screen. It will be understood that during this and other washing operations the beater is preferably continuously actuated so that the stock is thoroughly agitated, and settling is avoided. This insures that each particle of the fiber is thoroughly and eillciently washed. This washing of the fibers is continued for a period of from 10 to 15 minutes after which the valves controlling the water inlet and exit pipes are closed.

To cook or strip the stock, the necessary chemicals are now introduced into the beater. In the present instance, the chemicals comprise .187 pound of sodium hydrosulte and one pound of flaked sodium hydroxide.

After the chemicals have been introduced, live steam is introduced through the valve 81 at twenty pounds of pressure, and with the knives of the beater fully separated as before, the contents of the-beater are vigorously circulated. Also, during this time it will be found advantageous to admit steam also to the jacket through the pipe 1I. After a temperature substantially corresponding to 20 pounds steam pressure has been reached, this temperature is maintained .for about 40 minutes, after which the admission of steam is discontinued and the pressure is relieved to about 5 pounds per square inch by opening the valve 22a. Cold water is then admitted through the valve 88, and the stock is circulated and washed for about '75 minutes during which time pressure in the beater is maintained at about 5 pounds per square inch. It will be understood that when washing or circulating water through the beater, the beater is completely filled with stock and water and the liquid flows out through the pipe 22 at the same speed at which liquid is admitted through the water inlet valve 88.

Under the conditionsof the treatment herein specified, the rags are converted into a stock satisfactory for bleaching without further treatment. This bleaching is readily effected in the beater where the bleaching can be effected by the use of hypochlorite or, if desired, chlorine gas introduced as near the bottom of the beater as possible may be employed. Sulfur dioxide can be used to supplement chlorine or it can be used alone.

In all of the above operations, it is found to be advantageous to work the stockv at a relatively high consistency, for example about 6 to 9 percent. Compared with the earlier treatment steps, this consistency obviously is somewhat reduced in the final bleaching step. After the bleaching has been completed, the stock is again washed and is ready to be introduced into the furnish without further treatment except the usual beating step. This nal beating of the stock may be effected in another beater in the usual manner or it may be carried out in this same .special beater in which the above described process steps are effected, in which case, of course, the spacing of the knives 2l and 25 is reduced in accordance with the usual practice. In order to preserve the strength of the finished stock, it may be advisable to prevent rise oi' temperature during the beating operation by circulating cold water through the jacket.

The cooking temperature can be varied according to conditions, but ordinarily it is not advisable to use more than 40 pounds steam pressure equivalent to 130 C. because at higher temperatures certain dyestufis are modiiled to rather stable form which is correspondingly diillcult to eliminate. On the other hand, a fairly high temperature speeds up the treatment so that a temperature of at least C. for the cooking, is usually indicated.

Many indigo dyed denims are sized with wax which usually has a melting point of between 50 and 60 degrees C. In order to effect proper elimination of this material, it should be kept in a finely emulsified condition during the entire operation, so that it will flow out through the screen.l

he temperature and time for cooking and strippingdepend in part on the nature of the dyestuil.' and the condition of the rags. New denims dyed with indigo respond successfully to the above described treatment. However, with other dyestuifs there may be a distinct advantage process to even more stable chemical modification than the original color. For example, in the case of goods dyed with indanthrene. we prefer to carry on the stripping operation at a substantially higher temperature (35 pounds of steam` equal to 127 C.) for a shorter time (10 minutes) than in the case of rags dyed with indigo.

'I'he amount of chemicals employed in the stripping process depends upon the quantity of dyestuff present. For denim rags we prefer to use caustic soda in the amount of 4% of the rag weight, and sodium hydrosulte in the amount of aboutthree-fourths of 1% of the rag weight. Alkaline agents other than caustic soda may be employed, although we prefer caustic soda for rags dyed with indigo. On the other hand, for the purpose of treating shirt cuttings containing indanthrenes, calcium hydroxide appears to be preferable. As stated before, 4%, or between 3 lto 5 percent of the rag weight is desirable for use where sodium hydroxide is selected as the alkali to be used, whereas when lime is used, about double that amount is indicated.

Various modifications of the process and of the apparatus will occur, to those skilled in the art. Therefore, it is to be understood that the scope of the invention is to be determined by reference to the appended claims.

We claim as our invention:

1. The steps in a process of preparing indanthrene dyed rags containing indanthrene for paper making, consisting in rst mechanically Working said dyed rags in water so as to divelicate the rags and form a suspension of separated fibers prior to a chemical treatment thereof, then treating said bers with an aqueous alkaline hydrosuiphite bath at an elevated temperature of about 100 to 130 C., and then washing said fibers.

2. The process of removing indanthrene from dyed rags containing indanthrene and preparing said rags for paper making, consisting in first diveilicating said rags in Water prior to a chemical treatment thereof, stirring the divellicated rags in a. sodium hydrosulphite bath at a temperature of about 100 to 130 C. in order to detach the indanthrene, and then washing the divellicated rags.

3. The process of removing indanthrene from dyed shirt cutting rags containing indanthrene and preparing said rags for paper making, which comprises diveliicating said rags in water prior to a chemical treatment thereof so as to form a suspension of separated bers, then circulating said fibers in the presence of live steam at a temperature of about 127 C. for about 10 minutes in a bath containing about 0.75 per cent rsodium hydrosulphite and about 8.0 per cent calicum hydroxide based on vthe weight of said rags, and then washing the bers to remove the indanthrene detached by the previous treatment.

HARRY F. LEWIS. STEPHEN I. KUKOLICH. 

